1. Field of the Invention
This disclosure relates generally to the field of subsea interventions. More specifically, the disclosure relates to devices and methods for cleaning subsea flex joints.
2. Background of the Technology
In many offshore operations, subsea pipestring or riser extending from subsea equipment to a rig or other structure at the surface of the water provides communication between the subsea well and the surface structure. For example, a completed subsea well may have a riser assembly that extends from the subsea production equipment disposed on the sea floor to a wellhead on the surface structure (e.g., productions platform). Such pipestrings and risers are usually constructed of a plurality of rigid pipe segments coupled together end-to-end by flexible pipe joints. This arrangement allows the riser to be laid out subsea in a non-vertical orientation, and then raised at one end and coupled to an offshore platform in a generally vertical orientation.
Subsea risers are typically supported in tension by the surface structure and affixed to the subsea equipment by a stress joint. Riser are subjected to a variety of loads and stresses while suspended from the surface. For example, ocean currents, wave motions and other external forces may create large bending stresses in the riser, which can lead to damage to and/or failure of the stress joint connecting the riser assembly to the subsea equipment. An uppermost joint proximal the surface structure is usually a swivel joint that allows for rotation of the riser assembly about its longitudinal axis, and the joints disposed between each rigid pipe section are usually flexible joints that allow bending of the riser. In other words, the flexible joints accommodate limited movement of the individual pipe sections relative to each other.
Moreover, there has been a continuing trend to employ offshore drilling and production facilities in increasingly deeper water and in geographical regions that experience harsh weather conditions such as the North Sea. Offshore drilling and production facilities in such dynamic ocean environments can experience extreme load conditions on the risers and mooring system components. Extreme weather conditions alone, or in combination with equipment failures, may result in complex, simultaneous translational and rotational motions of the platform.
Most conventional subsea flexible pipe joints for use in risers include component(s) constructed of elastomeric materials, which may become encrusted with marine life and/or algae. Such build-up on the elastomeric materials may make inspection of the flex joint for any signs of damage or malfunction very difficult. In the past, human divers were used to clean the elastomeric materials in subsea flexible joints using a water blaster. However, the use of divers is not a particularly desirable solution for cleaning subsea joints because of a variety of operational and safety issues. For example, the use of human divers requires a dive spread put on the production platform, typically requires a complete halt or reduction in platform operations during the dive, and due to subsea visibility, may be limited to daylight hours.
Accordingly, there remains a need in the art for devices and methods for safely cleaning subsea flex joints. Such devices and methods would be particularly well received if they cleaned subsea flex joints without necessitating the reduction or halting of other platform operations.